Maja Krzic

 
Prospective Graduate Students / Postdocs

This faculty member is currently not actively recruiting graduate students or Postdoctoral Fellows, but might consider co-supervision together with another faculty member.

Associate Professor

Research Classification

Agriculture

Research Interests

Soil science
Soil science education
Integration of multimedia and soil science

Relevant Degree Programs

 

Research Methodology

Integration of multimedia and soil science
Integration of information technology and soil science

Graduate Student Supervision

Doctoral Student Supervision (Jan 2008 - Mar 2019)
Soil properties and land use affecting soil water dynamics in Andisols and Inceptisols at two mid-elevation sites in the Colombian Andes (2018)

Soil has a crucial role in the terrestrial component of the hydrologic cycle, regulating the availability of water for ecosystem services. Yet relationships between soil properties and land use for the major soil types in the Colombian Andes have not been extensively studied. This study evaluated soil water (SW) dynamics of two soils types, belonging to the most common soil orders in the Colombian Andes, Andisols and Inceptisols. The research was conducted in two watersheds at mid-elevation, and focused on the relationships between mineralogical, physical and chemical soil properties with soil water dynamics, including soil water retention (SWR) and field saturated hydraulic conductivity (Kfs). The Andisols and Inceptisols of this study have a large total porosity compared to typical clay soils, but Andisols, showed higher SWR at every soil tension relative to Inceptisols. Notwithstanding the high hygroscopic water (θPWP), both soils have a wide pore size distribution, with similar gravitational water and plant available water storage capacities. Despite differences in climate and soil parent material between watersheds, the presence of colloids with high specific surface area in both soils (allophane, imogolite, ferrihydrite and organo-metallic complexes in Andisols and ferrihydrite and Al/Fe oxides in Inceptisols) contribute to high SWR. Within each site, differences in SWR between land uses appear minimal, although soil organic carbon was lower under pasture in both soils. The limited differences in SWR between natural forest and pasture appear to reflect the effects of short-range order (SRO) minerals and organo-metallic compounds on SWR, which offset differences in SOC between natural forest and pasture.Quasi steady-state infiltration rates measured in the field did not correspond to expected values based on texture alone, highlighting the importance of field based measurements, particularly in soils with SRO minerals. Additionally, there was a pronounced seasonal difference in Kfs under pasture in both soil types, and a negative correlation of soil water content with Kfs in Inceptisols. Determination of physical, chemical and mineralogical properties was found to be crucial in understanding soil water dynamics in this study, and future work should include an assessment of SRO minerals in addition to SWR characteristics.

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Relative bulk density as an index of soil compaction and forest productivity in British Columbia (2009)

Soil compaction often limits conifer regeneration on sites degraded by construction of landings and roads, but inadequate understanding of compaction characteristics has sometimes led to inappropriate rehabilitation efforts. This warrants development of new methods to assess compaction and its relation to tree growth. The objective of this study was to develop a high-level integration indicator that will characterize compaction of forest soils and that could be correlated to tree height growth. Mineral particle density of soils from interior British Columbia (BC) forests varied significantly among the geographic locations. Oxalate-extractable Fe- and Al-oxides and particle size distribution (PSD) were related to soil and mineral particle densities, while soil organic matter (SOM) and Al- and Fe-oxides were important soil properties in relation to soil particle density. The significance of levels of single soil properties in predicting maximum bulk density (MBD) were in the order: plastic and liquid limits, organic matter content, oxalate-extractable oxide, and PSD. Stratification of the sample according to Atterberg limits improved the predictability of MBD, and variation in particle density was included in the prediction by other soil properties used in the models. Height growth of interior Douglas-fir (Pseudotsuga menziesii var. glauca [Bessin] Franco) was restricted when relative bulk density (RBD) was > 0.72. For lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) and hybrid white spruce (Picea glauca [Moench] Voss × engelmannii Parry ex Engelm.), an RBD of 0.60 - 0.63 corresponded to maximum height growth, while that of 0.78 - 0.84 appeared to limit height growth. The presence of surface organic material mitigated compaction and was often associated with lower RBD. Interior Douglas-fir and lodgepole pine planted in low elevation sites in north-central BC did not grow well and their height growth was weakly related to RBD. The results suggest that soil rehabilitation should be considered on disturbed sites where soil RBD is > 0.80.Findings in this study have implications in assessing forest soil compaction and its effect on site productivity. The results will help predict soil behaviour and associated tree growth in response to timber harvesting and site rehabilitation.

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Master's Student Supervision (2010-2017)
Ammonia emissions and dry deposition from broiler barns in the Fraser Valley of British Columbia (2016)

Ammonia emissions from commercial broiler operations have been noted as one of the potential contributors to the nitrate contamination of the Abbotsford-Sumas aquifer in southwestern British Columbia (BC). The localized dry deposition of this emitted ammonia was of special interest and had not been measured in any comparable climate. Three barns, on two farms, located on the aquifer were assessed from July 2011 to June 2012. Ventilation, emission, and deposition samples were taken weekly throughout the seasons to accurately characterize the impact on the local environment. Ventilation was measured using a Fan Assessment Numeration System and timers that recorded individual fan activity. Acid impinger traps were used to measure the ammonia emitted by the sidewall fans. A methodology for measuring dry deposition by exposing air-dried soil was modified to use small Petri dishes and a 24-hr exposure time. The modified dry deposition method was found to be robust and effective for the requirements of this study. Dishes of soil were placed 2.1 and 3.6 m in front of and between each fan, as well as around the barns and farm properties. Ventilation rates for the barns were significantly and positively correlated with bird age and exterior temperature. Ammonia emissions were correlated with bird age and the emission factors for the three barns ranged from 0.19-0.37 g NH₃ bird-¹ day-¹ with annual ammonia emissions for each barn reaching 600 to 815 kg NH₃. Dry deposition levels on the two farms exceeded 50 kg NH₃ annually although this accounted for less than 10% of the ammonia emitted. The deposition levels were highest near the barns and were concentrated directly under the sidewall fan hoods. These levels of ammonia show significant potential to cause nitrate to leach into the groundwater and further contaminate the aquifer but future work and upscaling of data collection are needed.

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Blending multimedia and campus-based learning to enhance learning about forest floor and humus forms (2015)

Given the functions of forest organic soil horizons in carbon sequestration, biodiversity and nutrient cycling, coupled with the fact that the forest floor is often not described in soil surveys, it is important that forestry professionals learn to classify organic horizons and humus forms. The current generation of undergraduate students appreciate having access to multimedia and online resources in their learning, and prefer active, collaborative experiences of the concepts they are learning in the classroom. With technological advances, modernizing curriculum by blending campus-based learning and multimedia is ever easier to accomplish. The objectives of this study were to: (1) develop blended-learning activities, combining campus based learning and multimedia web-based resources, to teach forest floor description and classification; and (2) conduct exploratory factor analysis of student survey responses to assess student opinions about the application of the blended-learning method. The Forest Floor web-based educational resource and campus-based activities were developed with the contributions of a team of experts in soil science, web and multimedia design, and science education. Ninety-four percent of students agreed or strongly agreed that the Forest Floor web-based resource was helpful for learning forest floor concepts, 79% that describing samples in class was essential for understanding the properties of organic horizons, and 81% that they were able to relate information in the Forest Floor web-based resource to their own samples used in an in-class activity indicating that students appreciated the blended learning methodology. Based on the survey responses five implicit factors were interpreted: (1) satisfaction with the web-based educational resources as learning enhancements; (2) success of presentation of concepts using a blended learning method; (3) student self-assessment of learning; (4) student learning preferences in accessing materials; and (5) website usability. Student feedback suggests that the blended learning activities were appreciated and met the learning objectives. This study also provides an example for conducting exploratory factor analysis of blended learning interventions and provides factors that may be verified through confirmatory factor analysis.

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Effects of grassland set-asides on selected soil properties in the Fraser River Delta of British Columbia (2014)

Grassland set-asides (GLSAs) have been used to encourage environmental stewardship on agricultural land in the Fraser River delta of British Columbia (BC) since 1994. Through this Grassland Set-aside Stewardship Program, farmers plant a mixture of grasses and legumes in place of harvestable crops for a minimum of one full year and the farmers then receive payment for establishing these short-term grasslands. Grassland set-asides are typically established on degraded fields. Although improving long-term soil quality is a key objective in the GLSA Program, evaluations of GLSA management effects on the soil have been few and limited in scope. The objectives of this study were to determine the effects of GLSA management and GLSA age on selected soil properties in agricultural fields in the Fraser River delta. Three GLSA field sites – ranging in age from two, three, and six years – were compared to three adjacent cropped potato fields for the following soil properties: total soil C and N, mechanical resistance, bulk density, aeration porosity, and aggregate stability. Relative to the Cropped treatment, the GLSA treatment did not result in an increase in total soil C or N, but did result in lower soil mechanical resistance in the upper 30 cm depth, and higher aeration porosity, and aggregate stability. The differences observed between the Cropped and GLSA treatments were most pronounced on the site with the six-year-old GLSA, indicating reduced compaction and improved soil structure as a GLSA ages. Baseline measurements of the soil prior to GLSA establishment are recommended to track changes to the soil over time and to improve the efficacy of GLSA management as a remediation strategy by pinpointing underlying soil issues that could be addressed through other corrective management (i.e. sub-soiling, liming, etc.). Soil mechanical resistance, aeration porosity, aggregate stability, pH, salinity, and mineralizable N are suggested as valuable, responsive indicators of GLSA management effects on the soil.

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Plant community relationships to soil properties and topography in a southern interior BC grassland : a refinement (2012)

The grasslands of British Columbia, Canada are an asset to the province’s biodiversity, economy, natural beauty, and recreation. Since the late 1800s, these areas have been largely modified and reduced, and they are currently threatened by climate change and exotic plant invasions. The ability of land managers to adapt to the effects of climate change and plant invasion depends on having the best possible understanding of these systems; however, little quantitative information is available on the strength of relationships between topography, soil properties, and plant community composition. I collected data on plant communities, selected soil properties, and topography on 31 sites in Lac du Bois Provincial Grasslands Park in southern interior British Columbia during May-July 2010. Cluster analysis (UPGMA) and multi-response permutation procedures (MRPP) of my data produced more homogeneous groups of sites by vegetation (A=0.29, p=0.001) and soil properties (A=0.22, p=0.001) than for two currently used grassland classification systems that are based on elevation ranges (A=0.17, p=0.001; A=0.15, p=0.001). Non-metric multidimensional scaling (NMS) confirmed the distinctiveness in overall species composition and main environmental correlates for the three main plant communities: bluebunch wheatgrass/big sage, bluebunch wheatgrass/rough fescue, and rough fescue/Kentucky bluegrass. The Mantel (multivariate) correlation between plant community composition and soil properties was stronger on north-facing sites (0.58) than on south-facing sites (0.19), while the Mantel correlation between topography and soil properties was stronger on south-facing sites (0.38) than on north-facing sites (n.s.). These correlations indicate stronger plant-soil feedbacks on north-facing slopes, while on south-facing slopes the effect of slope angle on heat and desiccation stress is the most important factor shaping plant communities. The highest occurrences of invasive species in the study area were at the higher elevations, likely in response to increasing precipitation, lower temperatures, and higher soil fertility at the higher elevations. The information provided in this thesis can aid land managers by adding to current knowledge about the relationships between plant communities, soil properties, and topography, which is important for predicting effects of future climate change and the spread of invasive plant species.

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A comparison of the effects of 20 and 30 years of grazing on grassland soil properties in southern British Columbia (2011)

Although numerous studies have been conducted on rangeland soil quality in Alberta, Manitoba, Saskatchewan, as well as in the Great Plains, there has been little documentation of the response of soil properties to time of grazing and stocking rate treatments for the grasslands of the southern interior of BC. In the Lac Du Bois range in Kamloops, BC, the current moderate stocking rate of 2 AUM ha⁻¹ was based on a desired available forage use of 50%. Livestock is moved up and down an elevation and productivity gradient over the grazing season so that pastures located midway up the gradient are grazed either in the spring or fall. The objectives of this study were to determine (1) the effects of spring and fall grazing treatments on selected soil properties after periods of 20 and 30 years and (2) the effects of 0 and 2 AUM ha⁻¹ grazing rates on selected soil properties after periods of 20 and 30 years. The spring grazing treatment led to greater soil bulk density, mechanical resistance, pH, as well as lower polysaccharides and CEC relative to the fall grazing treatment. The grazing rate of 2 AUM ha⁻¹ led to greater soil mechanical resistance and pH, as well as lower soil polysaccharides and LOMF relative to the ungrazed control. After 30 years of grazing, soil bulk density was greater in the 0-7.5-cm depth under the 2 AUM ha⁻¹ treatment relative to the ungrazed exclosure in spring-grazed but not in fall-grazed areas, indicating that this stocking rate, when used for spring grazing, has led to soil compaction. Rangeland managers in the southern interior of BC should consider adjustments of time of grazing and stocking rate recommendations when these have been solely on vegetation responses, and should consider including soil properties in rangeland health assessments.

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Development of an innovative web-based teaching tool illustrating land use impacts to soil quality and formation (2010)

No abstract available.

 
 

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